Amphibious vehicle cooling systems

ABSTRACT

Planing amphibious vehicle ( 101 ) comprises engine ( 105 ) with internal cooling ducts ( 106 ). The engine is cooled first by air-water exchanger ( 102 ), and secondly by water-water exchanger ( 108 ). One or both exchangers may be located in compartment ( 119 ), separated from engine compartment ( 117 ) fully by bulkhead ( 80 ) (FIG.  4 ), or partially by bulkheads ( 118, 120 ). External water for exchanger ( 108 ) is drawn in from outside hull ( 109 ) through jet intake ( 114 ), the through inlet ( 115 ) in jet drive duct ( 116 ); and exhausted through outlet ( 123 ). Compartment ( 119 ) may also contain exhaust silencer ( 121 ). Numerals ( 103  and  104 ) denote grilles; ( 107 ) denotes cooling fan(s). FIG.  2  shows an alternative arrangement, with external water drawn from beneath the hull by pump ( 32 ). FIG.  1  shows front mounted radiator ( 2 ), covered by external flap ( 4 ) allowing air cooling to be shut down on water. FIG.  3  shows a water-water exchanger combined with the marine jet drive.

The present invention relates to the cooling of internal combustionengines in amphibious vehicles, hereafter called amphibians;particularly for planing amphibians. The term external water is used todefine water drawn in from outside the amphibian for cooling purposes;whereas the term internal water is used to denote water circulatingentirely and solely within the amphibian for cooling purposes.

Inboard mounted internal combustion engines used to drive small marinecraft are almost invariably directly cooled by water. This is pumpedfrom the water around the craft directly via a filter through the engineblock and thence overboard. This may necessitate measures to preventinternal corrosion of the engine.

Land vehicles, apart from a few which are air cooled, employ indirectmeans whereby liquid coolant is circulated through the engine block fromand back to a heat exchanger, that is a radiator, which is cooled by airdirected through the exchanger.

The problem with amphibians is that the sole provision of direct watercooling is not feasible because the vehicle may be on land, and airintakes for indirect cooling radiators cannot always be located inconvenient positions. Furthermore, the difficulty of mounting a radiatorin a convenient position may result in precious space being taken up byair ducts or fans or both.

External water-water heat exchangers have been tried on amphibians, buthave two notable drawbacks. One is that they are susceptible to damage,particularly from foreign objects; the other is that they inhibit marineperformance and reduce hydrodynamic efficiency by breaking up theotherwise smooth contour of the underside of the hull.

A planing amphibian engine cooling system according to the inventioncomprises liquid coolant ducting for circulating the coolant around theengine, a heat exchanger connected to the ducting and arranged so thatair may be passed from an air inlet through the first exchanger to coolthe coolant circulated around the engine, and a second beat exchangerconnected to the dust and arranged so that external water may be passedthrough a water inlet on the underside of the hull from outside the hullto inside the hull, then through the second exchanger to cool thecoolant, the water inlet being within the rear two thirds of the lengthof the hull. The invention also comprises an amphibian having the abovesystem.

The arrangement of the invention is such that when the vehicle is in thewater, air cooling arrangements may be closed down whereby air intakesmay be shut to protect air cooled heat exchangers. This will not onlyprotect the heat exchanger matrix from foreign object damage, but alsoprevent external water flooding the radiator compartment and affectingvehicle handling and stability. Furthermore, unlike the arrangements inU.S. Pat. No. 4,730,664 (Forsthuber et al), the heat exchanging can becompact with an air cooled exchanger located near upper intakes and awater cooled exchanger located as low down in the vehicle as possible toensure good stability in the water. The location of the water inletwithin the rear two thirds of the length of the hull ensures that as thevehicle moves from displacement mode to planing mode, there is acontinuous flow of cooling water ensured by the presence of a smallpressure greater than atmospheric pressure.

Whilst it would theoretically be attractive to change from indirect todirect cooling when entering the water, there would be a difficult andcritical time at the tune of entry where air ducts were prone to damageand yet water cooling was not available due to incomplete entry. Forsimplicity and safety, it is therefore preferred to employ indirectcooling for both land and water modes. This also allows retention ofantifreeze with its associated corrosion inhibitors in the enginecoolant ducting, to protect the engine during winter storage and/ordriving of the amphibian.

Preferably a cooling water pump is provided to circulate water fromoutside the amphibian of the invention through the second heat exchangerto avoid reliance on air cooling through the first exchanger whilst theamphibian is stopped. Alternatively, external water may be arranged tobe taken from the pressurized side of a marine jet drive to the secondheat exchanger. This saves the weight and cost of a discrete coolingwater pump used specifically to feed the second exchanger.

A second alternative arrangement comprises a second heat exchangercombined with the marine jet drive. This could be in the form of ajacket for internal water surrounding the jet drive. In addition,cavities in the jet drive hub and/or stator blades may be used, asdescribed in our co-pending application, GB2,363,453A, the contents ofwhich application are incorporated herein by means of reference. Thisarrangement has the advantage of not requiring any external waterplumbing within the vehicle, other than the jet drive itself.Furthermore, the entire trust of the jet unit is available for vehiclepropulsion, without any pressure being used for circulating water withinthe vehicle.

In one embodiment of the invention, the first exchanger is mounted inthe front of the vehicle behind an air intake located above the vehiclestatic water line. This is particularly suitable for a planingamphibian, where the bow will ride higher in the water than that of adisplacement vehicle. Alternatively, the first exchanger may be locatedbehind closure means comprising one or more closable flap(s). The flapor flaps not only protect the exchanger from the surrounding water whenthe vehicle is travelling fast, but also from flotsam. The flap(s) canbe provided with a simple hinged opening and closing arrangement.

Fast amphibians require a water inlet to be nearer the stern. Forexample, a planing amphibian will require the water inlet to be in theback half of the hull. For best results when the vehicle is tramping, ithas been found that the water inlet should preferably be located between60% and 95% of the distance from front to back of the waterline on theplane, and more preferably between 70% and 90% of the distance fromfront to back. A water inlet in such a location beneath the hull isplaced near the centre of pressure for a planing vehicle, thus ensuringa plentiful supply of water.

Embodiments of the invention will now be described by way of examplewith reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic side elevation of an amphibian with a radiatorin the front;

FIG. 2 is a diagrammatic side elevation of an amphibian with a radiatorat the rear;

FIG. 3 is a diagrammatic side elevation of an alternative layout of anamphibian with a radiator at the rear,

FIG. 4 is a diagrammatic side elevation of a further alternative layoutof an amphibian with a radiator at the rear, and

FIG. 5 is a diagrammatic side elevation of a yet further alternativelayout of an amphibian with a radiator at the rear.

In all of these figures, the road wheel and marine transmissions havebeen omitted for clarity, as have various brackets and supports; exhaustpiping and electrical wiring; the radiator header tank and any oilcoolers fitted. These parts will clearly be necessary for thefunctioning of the amphibian, but do not form part of the invention, andtherefore will not be described in detail. In all cases, a filter (notshown) may be fitted to the water inlet for the second exchanger, toprotect said exchanger from blockage and/or damage by foreign objects.Furthermore, components have been shown in such orientations as to makethe figures clear, and therefore may in practice be in alternativealignments for functional or packaging reasons.

Although the general principles of the invention could be applied toamphibians with front-, mid-, or rear-mounted engines, and with eitherdisplacement or planing hulls, they will be described with particularreference to a mid-engined planing amphibian.

In FIG. 1, where the amphibian generally shown at 1 is mid-engined, afirst heat exchanger (i.e. radiator) 2 is located behind an air inlet 3,which may be closed by means of a hinged flap 4. The engine 5 hasinternal coolant ducting represented schematically by broken lines 6.Ducting 6 is connected to the first heat exchanger 2 via a second heatexchanger 8 and piping 10, 11. The second heat exchanger 8 is cooled bywater pumped by pump 12 through piping 14 venting into pump jet duct 16.First exchanger 2 is ideally located to take advantage of forwardmovement when on land, but requires the closure flap 4 and lengthypiping 10, 11.

FIG. 2 shows a cooling system in which engine 25 for vehicle 21 iscooled in the same way as the previous embodiment, except that firstexchanger 22 is located at the rear of the vehicle enabling piping 30connecting exchanger 22 to engine ducting 26 to be shortened. Pipe 31connecting first exchanger 22 to second exchanger 28 is likewise shorterthan pipe 11 in the first embodiment. The water for second exchanger 28can be fed by piping 34, venting as before into pump jet duct 36.Numeral 23 denotes a radiator grille. A fan 27 is shown in schematicform. A typical water line for planing is shown at 37.

FIG. 3 shows a cooling system in which engine 45 for vehicle 41 iscooled in the same way as the previous embodiment, by a first exchangerlocated at the rear of the vehicle. In this case, pipe 51 connects firstexchanger 42 to second exchanger 48, which is arranged as a jacketaround marine jet drive 56. As shown in the figure, this jacket isarranged to drive water around the outside of jet drive 56 from port 55to port 57, without taking a short cut straight across from one port tothe other. It will be seen that there is no pump in this arrangementother than the engine water pump, which may require to be upgraded tocope with the longer water pipes.

FIG. 4 shows a further amphibian where the first exchanger is located ina second compartment separate to the engine compartment, as described inthe applicant's co-pending application, published as WO 02/070289.Amphibian 61 has a mid-mounted engine 65 with cooling ducting 66. Firstexchanger 62 and second exchanger 68 are located in a compartment 79,which separated from the engine by a bulkhead 80. Air passes intocompartment 79 through grille 63, through exchanger 62, past one or moreexhaust silencers 81, and out through further grille 64. Air flow may beassisted by one or more fans 67. Although it is not essential thatexchanger 68 is located in compartment 79, this may be convenient forassembly and routing of water pipes. Exhaust silencer 81 is also locatedin compartment 79, and has a tailpipe 82 passing through grille 64. Theback part of the amphibian hull 69 is cut away at 84 to allow fitmentand operation of trim tabs, also the steering nozzle (not shown) andreversing bucket (where fitted) for the jet drive. In the embodimentshown, water is first drawn into the hull through the jet drive intakebelow the hull, then tapped off from the pressurized side of the jetthrough inlet pipe 74 in jet pump duct 76. As can be seen from thefigure, inlet pipe 74 is initially outside the hull, but passes throughit. The external water outlet 83 from the second exchanger can be seenat the transom 85.

FIG. 5 shows a yet further amphibian where the first exchanger islocated in a second compartment separate to the engine compartment.Amphibian 101 has a mid-mounted engine 105 with cooling ducting 106,located in engine compartment 117, limited by a forward bulkhead 113.First exchanger 102 is located at the top of compartment 119, which isseparated from the engine by a bulkhead. As this bulkhead does not fullyseal compartment 119 from engine compartment 117, it is shown as anupper bulkhead 120 and a lower bullhead 118. Outside air passes intocompartment 119 through grille 103, as shown by arrows; and is drawnthrough exchanger 102 by one or more fans 107, then exhausted pastsilencer 121 and out of the vehicle through grille 104. In thisembodiment, exchanger 108 is located in compartment 117. Hoses or pipes110, 111 connect the engine to the first exchanger, and the firstexchanger to the second, in a similar fashion to previous embodiments.However, in this case, engine 105 has a separate cooling systemcomprising further air intakes and fans (not shown). These blow airthrough compartment 117, and out through compartment 119. It isimportant that first exchanger 102 should have an intake of ambienttemperature air, rather than pre-waned air from engine compartment 117;so upper bulkhead 120 is arranged to seal off the intake to exchanger102 from the exhaust air from compartment 117. External water for thesecond exchanger is first drawn into the hull through the jet driveintake 114 below the hull, then tapped off from the pressurized side ofthe jet through inlet pipe 115 in jet pump duct 116. An alternativerepresentation of the piping through the second exchanger is shown ascompared to the FIG. 4 embodiment, to clarifier the external water flowthrough the second exchanger.

It will be appreciated that further modifications to the layout ofcomponents may also be made as required without departing from thespirit and scope of the invention. In particular, it may be foundconvenient to fit radiator 102 at a different angle, or in a yet furtherposition, to that shown. Exhaust silencer 121 may also be located aheadof radiator 102.

1. A planing amphibian engine cooling system comprising liquid coolantducting for circulating the coolant around the engine, a first heatexchanger connected to the ducting and arranged so that air may bepassed from an air inlet through the first exchanger to cool the coolantcirculated around the engine, and a second heat exchanger connected tothe ducting and arranged so that external water may be passed through awater inlet on the underside of the hull from outside the hull to insidethe hull, then through the second exchanger to cool the coolant, thewater inlet being within the rear two thirds of the length of the hull.2. A cooling system according to claim 1, characterized in that the airinlet is provided at the front of the vehicle, above the static waterline.
 3. A cooling system according to claim 1 or claim 2, characterizedin that the air inlet is provided with closure means so that it may beclosed when the amphibian is on water.
 4. A cooling system according toclaim 3, characterized in that the closure means comprises one or morehinged flaps.
 5. A cooling system according to claim 1, characterized inthat the amphibian has a mid-mounted engine.
 6. A cooling systemaccording to claim 1, characterized in that external water for saidsecond exchanger is arranged to be taken from the pressurized side of amarine jet drive.
 7. A cooling system according to claim 1,characterized in that external water for said second exchanger isarranged to be drawn into the vehicle by a cooling water pump.
 8. Acooling system according to claim 1, characterized in that the inlet forexternal water is located at a position between 60% and 95% of thedistance from the front to the back of the waterline on the plane.
 9. Acooling system according to claim 8, characterized in that the inlet forexternal water is located at a position between 70% and 90% of thedistance from the front to the back of the waterline on the plane.
 10. Acooling system according to claim 1, characterized in that the secondexchanger is combined with the marine jet drive.
 11. A cooling systemaccording to claim 10, characterized in that the second exchangercomprises a cooling water jacket around the marine jet drive.
 12. Acooling system according to claim 10, characterized in that the secondexchanger comprises cooling water passages through the marine jet drivestator blades.
 13. A cooling system according to claim 12, characterizedin that the second exchanger comprises cooling water passages throughthe marine jet drive hub.
 14. A cooling system according to claim 1,characterized in that the first exchanger is located in a secondcompartment separate to the engine compartment.
 15. A cooling systemaccording to claim 14, characterized in that the second exchanger isalso located in said second compartment separate to the enginecompartment.
 16. A cooling system according to claim 14, characterizedin that one or more exhaust silencers is also located in said secondcompartment separate to the engine compartment.
 17. (canceled) 18.(canceled)
 19. A cooling system according to claim 11, characterized inthat the second exchanger comprises cooling water passages through themarine jet drive stator blades.
 20. A cooling system according to claim15, characterized in that one or more exhaust silencers is also locatedin said second compartment separate to the engine compartment.